Rare earths release from dissolving atmospheric dust and their accumulation into crystallising halite: The Dead Sea example

The industrial extraction of Y and lanthanides (hereafter defined as Rare Earth Elements, REE) often requires the achievement of leaching procedures removing these metals from primary rocks and their transfer in aqueous leachates or incorporated in newly forming soluble solids. These procedures are the most dangerous to the environment in relation to the composition of leachates. Hence, the recognition of natural settings where these processes currently occur, represents a worthy challenge for learning how to carry out similar industrial procedures under natural and more eco-friendly conditions. Accordingly, the REE distribution was studied in the brine of Dead Sea, a terminal evaporating basin where brines dissolve atmospheric fallout particles and crystallise halite. Our results indicate that the shale-like fractionation of shale-normalised REE patterns in brines, inherited during the dissolution of atmospheric fallout, changes because of the halite crystallisation. This process leads to crystallising halite mainly enriched in elements from Sm to Ho (medium REE, MREE) and coexisting mother brines enriched in La and some other light REE (LREE). We suggest that the dissolution of atmospheric dust in brines corresponds to the REE extraction from primary silicate rocks, whereas halite crystallisation represents the REE transfer into a secondary more soluble deposit with reduced environmental health outcomes.

Trace element fractionation through halite crystallisation: Geochemical mechanisms and environmental implications

Halite is an important mineral for industry, agriculture and food production. It crystallises during water evaporation, and the progressive increase of dissolved metal ions in the brine occurs simultaneously. Thus, halite exploitation may deliver metal ions into the environment and the mechanism of this trace element accumulation has to be studied. In this work, we investigate the distribution of lanthanides and Y (hereafter called rare earth elements, REE), Zr and Hf between crystallising halite and brines in the Dead Sea as geochemical tools for recognising the mechanism of metal ion removal from brines and accumulation in halite. Halite forms cubic crystals where octahedral planes sometimes occur under particular thermal gradient conditions. Our findings indicate that crystal morphology influences the mechanism of metal ion removal from brines because octahedral surfaces are polar unlike those that are cubic. Accordingly, octahedra preferentially fractionate aqueous charged species such as [Hf(OH)₅]^-, compared to neutral species such as [Zr(OH)₄]⁰. Cubic surfaces do not fractionate aqueous species. In crystal cores, positive Eu anomalies occur suggesting Eu substitution for Na in the lattice. This substitution is energetically justified by ab initio calculations. Hf enrichment relative to Zr also occurs in primary halite-rich evaporites. It is not found in cubic halite from saltworks. The results of this study suggest that primary halite kinetically crystallised from brines can concentrate dissolved metal ions onto crystal surfaces where dissolved charged species are adsorbed. Accordingly, the dissolution of halite due to human activity can release these metal ions to the environment.

Overcoming barriers to vaginal hysterectomy: An analysis of perioperative outcomes

Objective

To determine perioperative outcome differences in patients undergoing vaginal hysterectomy based on uterine weight, vaginal delivery, and menopausal state.

Material and Methods

Retrospective chart review of 452 patients who underwent vaginal hysterectomy performed by a single surgeon. Patients’ age, vaginal delivery, uterine weight, previous pelvic surgery, previous cesarean delivery, removal of ovaries were compared, as well as estimated blood loss (EBL), operating room time (ORT), length of stay, intraoperative complications and postoperative complications. Multivariable logistic regression was used, and all data were analyzed at the level of p<0.05 statistical significance using SAS system software (SAS Institute Inc., Cary, NC), version 9.3.

Results

The mean age was 57.13±11.52 years and the median vaginal delivery was 2. The uterine weight range was 16.6-1174.5 g (mean 169.79±183.94 g). The incidences of blood transfusion and bladder injury were 3.03% and 0.66%, respectively. Factors shown to be associated with longer ORT included greater uterine weight, removal of ovaries, posterior repair, tension-free vaginal tape sling, prolapse, and EBL >500 mL (p<0.001). The factors associated with EBL >500 mL were greater uterine weight (p=0.001), uterine myomas (p=0.016) and premenopausal state (p=0.014). The factors associated with conversion to laparotomy were greater uterine weight (p<0.001) and premenopausal state (p<0.001).

Conclusion

Vaginal hysterectomy is a safe and feasible approach for patients desiring hysterectomy regardless of uterine weight and vaginal delivery.

The influence of body mass index on pregnancy outcome following single-embryo transfer

PURPOSE

The association between obesity and reproductive outcome is controversial. The aim of this study is to evaluate the effects of obesity on clinical pregnancy rates following transfer of a single fresh embryo.

METHODS

A retrospective cohort study was conducted at a single tertiary medical center, including all first, fresh, single-embryo transfers using non-donor oocytes, during 2008-2013. We compared clinical pregnancy rate and pregnancy outcomes of singleton live births resulting from the transfer of a single fresh embryo in normal weight, overweight, and obese women, defined as body mass index (BMI) < 25 kg/m², ≥ 25 BMI <30 kg/m², and BMI ≥ 30 kg/m², respectively.

RESULTS

Overall, 1345 cases met the inclusion criteria with 864 single-embryo transfers (SETs) in normal weight women, 292 in overweight women, and 189 SETs in obese women, resulting in 538 clinical pregnancies and 354 singleton births. The clinical pregnancy rate per transfer was similar among the three groups (41.3, 37.6, 37.5%, respectively, p = 0.416). Similarly, there were no significant differences in live births or ongoing pregnancies. On multivariate logistic regression analysis, BMI did not impact the likelihood for clinical pregnancy (OR 0.98, 95% CI 0.96-1.008, p = 0.216).

CONCLUSIONS

Our study demonstrated that obesity has no detrimental effect on the clinical pregnancy rate resulting from the transfer of a single fresh embryo.

Perioperative outcomes of robotic assisted laparoscopic surgery versus conventional laparoscopy surgery for advanced-stage endometriosis

Background and Objectives:

To determine perioperative outcome differences in patients undergoing robotic-assisted laparoscopic surgery (RALS) versus conventional laparoscopic surgery (CLS) for advanced-stage endometriosis.

Methods:

This retrospective cohort study at a minimally invasive gynecologic surgery center at 2 academically affiliated, urban, nonprofit hospitals included all patients treated by either robotic-assisted or conventional laparoscopic surgery for stage III or IV endometriosis (American Society for Reproductive Medicine criteria) between July 2009 and October 2012 by 1 surgeon experienced in both techniques. The main outcome measures were extent of surgery, estimated blood loss, operating room time, intraoperative and postoperative complications, and length of stay, with medians for continuous measures and distributions for categorical measures, stratified by body mass index values. Robotically assisted laparoscopy and conventional laparoscopy were then compared by use of the Wilcoxon rank sum, χ², or Fisher exact test, as appropriate.

Results:

Among 86 conventional laparoscopic and 32 robotically assisted cases, the latter had a higher body mass index (27.36 kg/m² [range, 23.90–34.09 kg/m²] versus 24.53 kg/m² [range, 22.27–26.96 kg/m²]; P < .0079) and operating room time (250.50 minutes [range, 176–328.50 minutes] versus 173.50 minutes [range, 123–237 minutes]; P < .0005) than did conventional laparoscopy patients. After body mass index stratification, obese patients varied in operating room time (282.5 minutes [range, 224–342 minutes] for robotic-assisted laparoscopy versus 174 minutes [range, 130–270 minutes] for conventional laparoscopy; P < .05). No other significant differences were noted between the robotic-assisted and conventional laparoscopy groups.

Conclusion:

Despite a higher operating room time, robotic-assisted laparoscopy appears to be a safe minimally invasive approach for patients, with all other perioperative outcomes, including intraoperative and postoperative complications, comparable with those in patients undergoing conventional laparoscopy.

Insulin Resistance and β-cell Function Calculated by Homeostasis Model Assessment in Lean, Overweight, and Obese Women with Polycystic Ovary Syndrome

OBJECTIVE

To evaluate the homeostasis model assessment (HOMA) measurement of insulin resistance (IR) and pancreatic β-cell function (%β) and compare those values between groups of healthy-weight, over-weight, and obese women with polycystic ovary syndrome (PCOS).

STUDY DESIGN

Retrospective cohort study of women aged 24-48 with PCOS, diagnosed according to 2004 Rotterdam criteria. Participants were grouped by BMI. Quantitative variables were compared by one-way ANOVA and the Tukey method. Analysis for power to detect a difference between means was conducted. Pearson correlation was used to test differences in frequency distribution.

RESULTS

By BMI category, 29 participants were of healthy weight, 11 were overweight, and 11 were obese. HOMA-IR was significantly higher in obese women as compared to overweight and healthy-weight patients (2.88 ± 2.09, 1.13 ± 0.73, 0.84 ± 0.49, respectively; p <0.0001). Moreover, HOMA-%β was significantly increased in obese women as compared to overweight and healthy-weight patients (186.89 ± 131.62, 106.83 ± 46.77, 86.60 ± 40.91, respectively; p<0.0001). Adequate statistical power was not present to distinguish a difference between overweight and normal-weight participants. A positive linear correlation was found between log HOMA-IR and BMI, and between log HOMA-%β and BMI.

CONCLUSION

Obese PCOS patients have a higher risk of elevated insulin resistance and β-cell function than do those with BMI <30.

Potential influence of the microbiome on infertility and assisted reproductive technology

Although an altered vaginal microbiota has been demonstrated to affect parturition, its role in assisted reproductive technologies is uncertain. Nevertheless, the effect of known pathogens such as Mycoplasma tuberculosis, Chlamydia trachomatis, and Neisseria gonorrhoeae is clear, causing subclinical changes thought to be risk factors in subfertility. The Human Microbiome Project (HMP) has allowed for metagenomic studies to aid in characterizing normal vaginal flora. Recent findings from the HMP demonstrate that many different species of Lactobacillus are present in the vaginal tract, with a few that predominate. Studies that characterize the vaginal microbiome in assisted reproductive technology support the hypothesis that colonizing the transfer-catheter tip with Lactobacillus crispatus at the time of embryo transfer may increase the rates of implantation and live birth rate while decreasing the rate of infection. In addition, there is some evidence that a progesterone-resistant endometrium might increase the risk of an abnormal vaginal microbiome.