Nanomaterials as Promising Additives for High-Performance 3D-Printed Concrete: A Critical Review.

Three-dimensional (3D) printed concrete (3DPC), as one of the subset of digital fabrication, has provided a revolution in the construction industry. Accordingly, scientists, experts, and researchers in both academic and industry communities are trying to improve the performance of 3DPC. The mix design of all kinds of concrete has always been the most crucial property to reach the best efficiency. Recently, many studies have been performed to incorporate nano- and micro-scale additives to ameliorate the properties of 3DPC. The current study aims to present the main design properties of 3DPC and completely cover both fresh and hardened state characteristics of 3DPC containing different nano- and micro-additives. Our observations illustrate that nanomaterials can be mainly utilized as a thickener to ameliorate the thixotropic behavior and the structural build-up of 3DPC, resulting in higher yield stress and better viscosity recovery. Furthermore, each nanomaterial, through its unique impact, can provide lower porosity and permeability as well as better mechanical strengths for 3DPC. Although much research investigate the fresh properties of 3DPC containing nano and micro additives, future studies are needed to provide better insight into the impact of these kinds of additives on the hardened characteristics of 3DPC. In addition, researchers may devote more research to address the effects of the additives discussed herein on the performance of other kinds of 3DPC such as lightweight, self-compacting, etc. It should be noted that the effect mechanism of nanomaterials on the inter-layer bond strength of 3DPC is another crucial issue that should be investigated in future studies. Furthermore, nano-scale fillers from source of waste and biomass can be attractive additives for future research to achieve high performance of sustainable 3D-printed concrete.

Teamwork skills in higher education: is university training contributing to their mastery?

Teamwork skills are considered essential for personal, academic and professional achievement, so universities are increasingly integrating them into their syllabuses. However, little is known about how some specific features of students and their educational development can affect their acquisition. Accordingly, this study aims to fill this gap and describe higher education students' mastery of teamwork skills and its relation to certain socio-academic variables (gender, academic year and grade point average-GPA). With the aim of determining the level of teamwork skills among university students, an observational, transversal descriptive study was designed with an intentional sample of Spanish university students. The sample is made up of 615 social science degree students. The results suggest significant gender differences, highlighting that female students outdid their male counterparts in most teamwork skills, except leadership. Likewise, students' skills improved as they progressed in their studies, particularly those skills related to adaptability and decision-making. Finally, a positive relationship was observed between teamwork skills and GPA, except for interpersonal development. A regression analysis confirmed the influence of both academic year and GPA for women whilst no effect was detected in the case of men. Based on these results, it is suggested to make changes in university education programmes to compensate for the influence of socio-academic factors and benefit from the most positive features of each gender regarding teamwork to achieve an equal and fair higher education.

Teamwork skills in higher education: is university training contributing to their mastery?

Teamwork skills are considered essential for personal, academic and professional achievement, so universities are increasingly integrating them into their syllabuses. However, little is known about how some specific features of students and their educational development can affect their acquisition. Accordingly, this study aims to fill this gap and describe higher education students' mastery of teamwork skills and its relation to certain socio-academic variables (gender, academic year and grade point average—GPA). With the aim of determining the level of teamwork skills among university students, an observational, transversal descriptive study was designed with an intentional sample of Spanish university students. The sample is made up of 615 social science degree students. The results suggest significant gender differences, highlighting that female students outdid their male counterparts in most teamwork skills, except leadership. Likewise, students' skills improved as they progressed in their studies, particularly those skills related to adaptability and decision-making. Finally, a positive relationship was observed between teamwork skills and GPA, except for interpersonal development. A regression analysis confirmed the influence of both academic year and GPA for women whilst no effect was detected in the case of men. Based on these results, it is suggested to make changes in university education programmes to compensate for the influence of socio-academic factors and benefit from the most positive features of each gender regarding teamwork to achieve an equal and fair higher education. (AU)

Effect of Multi-Walled Carbon Nanotubes on Strength and Electrical Properties of Cement Mortar.

This work aims to investigate the effects of multi-walled carbon nanotubes (MWCNTs) on the strength and electrical properties of cement mortar. MWCNTs were added to cement mortar in four different concentrations: 0.00 wt.%, 0.01 wt.%, 0.015 wt.%, and 0.02 wt.% by the mass of cement. The consistency, density, setting time and compressive and flexural strength of mixes were tested and analyzed at 28 and 90 days curing time. Mechanical performance tests confirm an increase of 25% and 20% in the ultimate compressive and flexural strength respectively, which results from MWCNT 0.02 wt.% loading at 90 days curing time. The resistivity measurements in mortars with 0.01 and 0.015 wt.% MWCNT loading result up to 10% decrement at both 28 and 90 days curing. Activation energy calculations show fully accordance with these statements, resuming that 0.01 wt.% MWCNT appears to be the most effective loading scheme to produce certain conductivity enhancement in cement mortar.

Sperm chromatin condensation and single- and double-stranded DNA damage as important parameters to define male factor related recurrent miscarriage.

The aim of the present work is to characterize the relationship between sperm protamine deficiency and single- and double-stranded DNA damage and to assess the diagnostic potential of chromomycin A3 (CMA3). For that purpose, semen samples from 90 human males with different clinical features were included (fertile donors, patients with recurrent pregnancy loss [RPL], and infertile patients). DNA condensation was analyzed by CMA3 and different types of DNA fragmentation were analyzed through the comet assay. A positive correlation between DNA condensation and single-stranded DNA fragmentation was found (Rs = .456; p = .05). CMA3 presented differences between fertile donors and all other groups (p < .001). Interestingly, patients with RPL, who were able to achieve a pregnancy, and infertile patients showed similar values of CMA3 (p > .05). Receiver operating characteristic curves and the profiles obtained by the combination of Comet assays and CMA3 indicate that the CMA3 test may be an interesting approach to distinguish those subjects with higher pregnancy loss risk from fertile donors (CMA3 area under the curve 0.928, with a confidence interval of 0.849-1.000). The present work shows that DNA condensation is related to oxidative damage, which affects mainly protamine-rich regions. The profiles observed in different clinical groups showed that CMA3 might be useful for the diagnosis of RPL risk when combined with Comet assays.

Proteomic Analysis in Seminal Plasma of Fertile Donors and Infertile Patients with Sperm DNA Fragmentation.

Seminal plasma proteomics studies could represent a new approach for the determination of molecular elements driving male infertility, resulting in a better male infertility characterization. The aim of this study is to investigate proteomic differences in seminal plasma samples from fertile and infertile individuals. For that, semen samples were selected according to semen analysis, clinical pathology, and values of sperm DNA fragmentation (alkaline and neutral Comet assay and Sperm Chromatin Dispersion test). A total of 24 seminal plasma samples classified in four groups were processed: fertile donors (FD), recurrent miscarriage patients (RM), asthenoteratozoospermic patients (ATZ), and asthenoteratozoospermic patients with varicocele (ATZ-VAR). Results obtained by 2D-differential gel electrophoresis (2D-DIGE) revealed 26 spots significantly increased in fertile donors when compared to patient groups. Also, eight spots in the ATZ group and two in the ATZ-VAR group were decreased compared to the other groups. Twenty-eight proteins were identified by mass spectrometry (MS), most of them involved in metabolic and cellular processes and with a catalytic or binding function. Protein-protein interactions through Search Tool for the Retrieval of Interacting Genes/Proteins (STRING) tool suggest that a large part of them were associated with each other. Furthermore, most of them were associated with ubiquitin C, indicating that it could play an important regulation role, resulting in a potential male infertility biomarker.

Controlled Synthesis and Microstructural Properties of Sol-Gel TiO2 Nanoparticles for Photocatalytic Cement Composites.

Titania nanoparticles are intensely studied for photodegradation applications. Control of nanoscale morphology and microstructural properties of these materials is critical for photocatalytic performance. Uniform anatase-type TiO2 nanoparticles were prepared by the sol-gel process using titanium isopropoxide as precursor. Controlled annealing up to 400 ℃ established crystallization and particle size ranging between 20 and 30 nm. Detailed thermal examination reveals that anatase phase transformation into rutile is affected by the annealing temperature and by the initial particle size. The anatase to rutile phase transformation occurs in the nanoparticles at 550 ℃. The Total Reflection X-ray Fluorescence (TXRF) study of the anatase nanoparticles shows a shift towards higher energy in the Ka Ti line of 10 eV, related to structural defects. These features were discussed in the photocatalytic behavior of several cement-based materials modified with the so-prepared anatase nanoparticles. The photocatalytic activity of the anatase-type TiO2/cement mortar system is evaluated from the degradation of Methylene Blue (MB) under UV irradiation, monitored through the absorbance at 665 nm. The results show that the photocatalytic composites exhibit up to 76.6% degradation efficiency. Mechanical testing of the nano-TiO2 modified cementitious composites evinces a moderate reinforcement of the strength properties at long ages.

Incidence of Induced Abortion in Uganda, 2013: New Estimates Since 2003.

BACKGROUND: In Uganda, abortion is permitted only when the life of a woman is in danger. This restriction compels the perpetuation of the practice in secrecy and often under unsafe conditions. In 2003, 294,000 induced abortions were estimated to occur each year in Uganda. Since then, no other research on abortion incidence has been conducted in the country. METHODS: Data from 418 health facilities were used to estimate the number and rate of induced abortion in 2013. An indirect estimation methodology was used to calculate the annual incidence of induced abortions ─ nationally and by major regions. The use of a comparable methodology in an earlier study permits assessment of trends between 2003 and 2013. RESULTS: In 2013, an estimated 128,682 women were treated for abortion complications and an estimated 314,304 induced abortions occurred, both slightly up from 110,000 and 294,000 in 2003, respectively. The national abortion rate was 39 abortions per 1,000 women aged 15-49, down from 51 in 2003. Regional variation in abortion rates is very large, from as high as an estimated 77 per 1,000 women 15-49 in Kampala region, to as low as 18 per 1,000 women in Western region. The overall pregnancy rate also declined from 326 to 288; however the proportion of pregnancies that were unintended increased slightly, from 49% to 52%. CONCLUSION: Unsafe abortion remains a major problem confronting Ugandan women. Although the overall pregnancy rate and the abortion rate declined in the past decade, the majority of pregnancies to Ugandan women are still unintended. These findings reflect the increase in the use of modern contraception but also suggest that a large proportion of women are still having difficulty practicing contraception effectively. Improved access to contraceptive services and abortion-related care are still needed.

Maternal Near-Miss Due to Unsafe Abortion and Associated Short-Term Health and Socio-Economic Consequences in Nigeria.

Little is known about maternal near-miss (MNM) due to unsafe abortion in Nigeria. We used the WHO criteria to identify near-miss events and the proportion due to unsafe abortion among women of childbearing age in eight large secondary and tertiary hospitals across the six geo-political zones. We also explored the characteristics of women with these events, delays in seeking care and the short-term socioeconomic and health impacts on women and their families. Between July 2011 and January 2012, 137 MNM cases were identified of which 13 or 9.5% were due to unsafe abortions. Severe bleeding, pain and fever were the most common immediate abortion complications. On average, treatment of MNM due to abortion costs six times more than induced abortion procedures. Unsafe abortion and delays in care seeking are important contributors to MNM. Programs to prevent unsafe abortion and delays in seeking postabortion care are urgently needed to reduce abortion related MNM in Nigeria.

The cost of postabortion care and legal abortion in Colombia.

CONTEXT: Although Colombia partially liberalized its abortion law in 2006, many abortions continue to occur outside the law and result in complications. Assessing the costs to the health care system of safe, legal abortions and of treating complications of unsafe, illegal abortions has important policy implications. METHODS: The Post-Abortion Care Costing Methodology was used to produce estimates of direct and indirect costs of postabortion care and direct costs of legal abortions in Colombia. Data on estimated costs were obtained through structured interviews with key informants at a randomly selected sample of facilities that provide abortion-related care, including 25 public and private secondary and tertiary facilities and five primary-level private facilities that provide specialized reproductive health services. RESULTS: The median direct cost of treating a woman with abortion complications ranged from $44 to $141 (in U.S. dollars), representing an annual direct cost to the health system of about $14 million per year. A legal abortion at a secondary or tertiary facility was costly (medians, $213 and $189, respectively), in part because of the use of dilation and curettage, as well as because of administrative barriers. At specialized facilities, where manual vacuum aspiration and medication abortion are used, the median cost of provision was much lower ($45). CONCLUSIONS: Provision of postabortion care and legal abortion services at higher-level facilities results in unnecessarily high health care costs. These costs can be reduced significantly by providing services in a timely fashion at primary-level facilities and by using safe, noninvasive and less costly abortion methods.

Double stranded sperm DNA breaks, measured by Comet assay, are associated with unexplained recurrent miscarriage in couples without a female factor.

It is known that sperm samples from recurrent pregnancy loss (RPL) couples have an increase in their sperm DNA fragmentation (SDF), but no studies have been performed in order to identify differences between single stranded SDF (ssSDF) and double stranded SDF (dsSDF) in these patients. This could be relevant because the type of DNA damage could have different effects. Semen samples were classified attending their clinical status: 25 fertile donors and 20 RPL patients with at least two unexplained first trimester miscarriages. SDF was analysed using alkaline and neutral Comet assay, SCD test and pulsed-field gel electrophoresis (PFGE), and ROC analysis including data from 105 more infertile patients (n = 150) was performed to establish predictive threshold values. SDF for alkaline and neutral Comet, and the SCD test was analysed in these categories of individuals. Data revealed the presence of two subgroups within fertile donors. The values obtained were 21.10±9.13, 23.35±10.45 and 12.31±4.31, respectively, for fertile donors with low values for both ssSDF and dsSDF; 27.86±12.64, 80.69±12.67 and 12.43±5.22, for fertile donors with low ssSDF and high dsSDF; and 33.61±15.50, 84.64±11.28 and 19.28±6.05, for unexplained RPL patients, also showing a low ssSDF and high dsSDF profile. This latter profile was seen in 85% of unexplained RPL and 33% of fertile donors, suggesting that it may be associated to a male risk factor for undergoing RPL. ROC analysis regarding recurrent miscarriage set the cut-off value at 77.50% of dsDNA SDF. PFGE for low ssSDF and high dsSDF profile samples and positive controls treated with DNase, to induce dsDNA breaks, showed a more intense band of about 48 kb, which fits the toroid model of DNA compaction in sperm, pointing out that some nuclease activity may be affecting their sperm DNA in RPL patients. This work identifies a very specific SDF profile related to the paternal risk of having RPL.

Health consequences of unsafe abortion in Colombia, 1989-2008.

The number of Colombian women hospitalized for the treatment of induced abortion complications increased from 57 679 in 1989 to 93 336 in 2008; the hospitalization rate also rose: from 7.2 to 9.1 cases per 1000 women aged 15-44 years. Factors that likely underlie the increase include improved access to postabortion care (although 1 in 5 women still do not obtain the care they need) and the growing role of misoprostol, often used incorrectly and to some extent replacing the use of surgical abortion by doctors. Efforts are evidently needed to improve access to safe abortion and effective contraception.

Induced abortion in Colombia: new estimates and change between 1989 and 2008.

CONTEXT: Although abortion was made legal in Colombia under selected circumstances in 2006, no national studies have examined whether the incidence of the procedure has changed since the previous estimate in 1989. METHODS: Data on the number of women treated for abortion complications were obtained from a nationally representative survey of 300 public and private health facilities, and estimates of the likelihood that women obtaining abortions experience complications and receive treatment at a facility were obtained from a survey of 102 knowledgeable professionals. Indirect estimation techniques were used to calculate national and regional abortion measures for 2008, which were compared with previously published 1989 estimates. Numbers and rates of unintended pregnancy were also calculated. RESULTS: In 2008, an estimated 93,300 women were treated for induced abortion complications in public and private health facilities. An estimated 400,400 induced abortions were performed, which translates to a rate of 39 per 1,000 women aged 15-44, a slight increase from 1989 (36 per 1,000). Rates varied widely across regions, from 66 in Bogotá to 18 in Oriental. Despite the new abortion law, only 322 legal abortions were performed in 2008. Between 1989 and 2008, the proportion of pregnancies ending in induced abortion increased from 22% to 29%, and the proportion of pregnancies that were unintended rose from 52% to 67%. CONCLUSION: Improvements in provision of and access to contraceptive and legal abortion services are needed to meet the increased demand among women and couples to prevent unintended pregnancy and unsafe abortion.

Aborto inducido y embarazo no planeado en Guatemala / Induced abortion and unintended pregnancy in Guatemala

Contexto: aunque la legislación guatemalteca permite el aborto inducido solamente para salvar la vida de la mujer, con frecuencia muchas mujeres obtienen abortos, en condiciones de riesgo y en respuesta a un embarazo no planeado. Estudios recientes indican que el aborto inseguro es un factor clave que contribuye a la morbilidad y mortalidad materna en el país; sin embargo, no existen datos a nivel nacional sobre la incidencia del aborto...

Early childbearing in Honduras: a continuing challenge.

(1) Honduras has the highest adolescent birthrate in Central America, at 137 births for every 1,000 15-19-year-olds. This rate has remained unchanged over the past two decades, despite declines in the birthrate among women in all other age-groups. In absolute numbers, births to adolescents increased by 50% between 1987 and 2001. (2) As of 2001, only one-third of all women aged 20-24 (and only one-seventh of those in rural areas) had completed primary school; less education is associated with a higher likelihood of early childbearing. (3) One-half of 20-24-year-olds give birth by age 20; this proportion is higher among the least-educated women (70%), the poorest women (64%) and those in rural areas (60%). (4) In 2001, 40% of all recent adolescent births were unplanned, and the highest proportion was among those with the most education (48%). Most sexually active 15-19-year-olds (70%) do not want to have a child in the next two years. (5) Despite these reproductive preferences, just one in three sexually active adolescents uses a modern contraceptive method. Overall, 48% of adolescents have an unmet need for effective contraception. (6) High levels of early childbearing coexist with low rates of professional prenatal and delivery care. In 2001, one-third of recent 15-24-year-old mothers did not make a single prenatal care visit. The same proportion gave birth without a medical professional in attendance. (7) Policies and programs that aim to promote adolescents' reproductive health and support their childbearing preferences exist, but they are often not fully implemented and need more official commitment and resources.

Early childbearing in Guatemala: a continuing challenge.

(1) Guatemala has the third highest adolescent birthrate in Central America-114 births for every 1,000 women aged 15-19 each year. (2) Only two-fifths of 20-24-year-old women have completed primary school. The proportion is one in four in rural areas and one in 10 among indigenous women. (3) One-half of young women enter into a union (formal or consensual) before their 20th birthday. Three-quarters of those with no schooling do so, compared with one-quarter of those with a primary education or more. (4) Forty-four percent of 20-24-year-olds were mothers by age 20; the proportion is highest among young women with no education (68%) and among indigenous women (54%). (5) The great majority of 15-19-year-old women in union-83%, with little variation by residence or ethnicity-do not want to have a child in the next two years. However, only 18% are using an effective contraceptive. (6) Although 70% of 15-24-year-olds who recently gave birth made at least one prenatal care visit, roughly half of the least educated and of indigenous women made none. Moreover, only half of 15-24-year-old mothers had professional medical care at their most recent delivery; the proportion is even lower among the least educated and indigenous women (one-quarter).

Induced abortion and unintended pregnancy in Guatemala.

CONTEXT: Although Guatemalan law permits induced abortion only to save a woman's life, many women obtain abortions, often under unsafe conditions and in response to an unintended pregnancy. Recent studies indicate that unsafe abortion is a key factor contributing to maternal morbidity and mortality in the country, but no national data on the incidence of abortion exist. METHODS: Surveys of all hospitals that treat women for postabortion complications and of 74 professionals who are knowledgeable about the conditions of abortion provision in Guatemala were conducted in 2003. Indirect estimation techniques were used to calculate the number of induced abortions performed annually. Abortion rates and ratios and the level of unintended pregnancy were calculated for the nation and its eight regions. RESULTS: Nearly 65,000 induced abortions are performed annually in Guatemala, and about 21,600 women are hospitalized for treatment of complications. Abortions occur at a rate of 24 per 1,000 women aged 15-49, and there is one abortion for every six births. The abortion rate is higher than average in the Southwest (less developed, mainly indigenous population) and Metropolitan (more developed, mainly nonindigenous population) regions (29-30 per 1,000 women). Over a quarter of all births are unplanned; combining unplanned births with abortions yields estimates that 32% of pregnancies in Guatemala are unintended, with an unintended pregnancy rate of 66 per 1,000 women. CONCLUSIONS: Unsafe abortion has a significant impact on women's health in Guatemala. Comprehensive government programs are needed to address the issues of unintended pregnancy and unsafe abortion, with attention to regional differences.

Early childbearing in Nicaragua: a continuing challenge.

(1) Among Nicaraguan women 20-24 years old, six in 10 had entered a union and almost half had had a child before their 20th birthday. (2) A quarter of all births in Nicaragua--35,000 per year--are to 15-19-year-olds. (3) Rural women, who have less education, on average, than their urban counterparts, are more likely than city dwellers to enter a union and become mothers during adolescence. (4) The proportion of 20-24-year-olds who had a child during adolescence is more than twice as high among the poorest as among those in the highest socioeconomic category. (5) Nearly half--45%--of births to adolescent women are unplanned, a level that varies little by women's urban-rural residence and their educational achievement. (6) Among all sexually active women aged 15-19 (in union and not in union), 86% do not want a child in the next two years, and 36% have an unmet need for effective contraception. Unmet need for family planning is equally high in urban and rural areas. (7) The strong link between low educational attainment and early motherhood suggests that improving educational opportunities for girls is a promising way of reducing high levels of adolescent childbearing in Nicaragua.

The incidence of induced abortion in Uganda.

CONTEXT: Although Uganda's law permits induced abortion only to save a woman's life, many women obtain abortions, often under unhygienic conditions. Small-scale studies suggest that unsafe abortion is an important health problem in Uganda, but no national quantitative studies of abortion exist. METHODS: A nationally representative survey of 313 health facilities that treat women who have postabortion complications and a survey of 53 professionals who are knowledgeable about the conditions of abortion provision in Uganda were conducted in 2003. Indirect estimation techniques were applied to the data to calculate the number of induced abortions performed annually. Abortion rates, abortion ratios and unintended pregnancy rates were calculated for the nation and its four major regions. Data on contraceptive use and unmet need were obtained from Demographic and Health Surveys. RESULTS: Each year, an estimated 297,000 induced abortions are performed in Uganda, and nearly 85,000 women are treated for complications. Abortions occur at a rate of 54 per 1,000 women aged 15-49 and account for one in five pregnancies. The abortion rate is higher than average in the Central region (62 per 1,000 women), the country's most urban and economically developed region. It is also very high in the Northern region (70 per 1,000). Nationally, about half of pregnancies are unintended; 51% of married women aged 15-49 and 12% of their unmarried counterparts have an unmet need for effective contraceptives. CONCLUSIONS: Unsafe abortion exacts a heavy toll on women in Uganda. To reduce unplanned pregnancy and unsafe abortion, and to improve women's health, increased access to contraceptive services is needed for all women.