Surface and thermal properties of synthesized cationic poly(ethylene oxide) gemini surfactants: the role of the spacer

The solubility and heat stability of surfactants are the prerequisites for their oilfield applications. Most commercial surfactants undergo hydrolysis at high temperature and prolonged heating at 40 °C or above leads to decomposition. In this report, three cationic poly(ethylene oxide) gemini surfactants (GSs) containing flexible and rigid spacers were synthesized for oilfield applications. The chemical structures of the GSs were elucidated with the aid of ¹³C NMR, ¹H NMR, FT-IR, and MALDI-TOF MS. The GSs exhibit pronounced solubility in deionized water, seawater, and formation brine and no cloudiness, phase separation, or precipitation were detected after keeping GS solutions in an oven at 90 °C for three weeks. According to thermal gravimetric analysis, the degradation temperature of all the GSs was above 240 °C, which is higher than the existing oilfield temperature (≥90 °C). The critical micelle concentration (CMC) of the synthesized GSs decreases upon increasing the temperature. Additionally, CMC values were observed to increase even further with increasing salinity. The low CMC values of gemini surfactants containing a flexible structure indicate that they create a more closely packed micelle structure compared with gemini surfactants with a rigid structure. The distinct surface and thermal features of the synthesized GSs reveal them to be appropriate materials for high salinity and elevated temperature reservoirs.

Synthesis of new cationic poly(ethylene oxide) gemini surfactants containing flexible and rigid spacer groups to tolerate harsh reservoir condition.     

Heavy metals transported through a multi-trophic food chain influence the energy metabolism and immune responses of Cryptolaemus montrouzieri

Ecotoxicology - Contamination of environment with heavy metals is increasingly becoming an issue of major concern across the globe. Heavy metals are highly toxic to humans as well as other...     

The influence of peripheral arterial disease on outcomes: a pooled analysis of mortality in eight large randomized percutaneous coronary intervention trials.

OBJECTIVES: We aimed to evaluate clinical outcomes among peripheral arterial disease (PAD) patients following percutaneous coronary intervention (PCI). BACKGROUND: A significant proportion of patients with coronary artery disease undergoing PCI have concomitant PAD, which may be associated with worse outcomes. METHODS: We performed a pooled analysis of 8 randomized PCI trials. We included multicenter PCI trials that compared antiplatelet therapies (EPIC, EPILOG, EPISTENT, RAPPORT, CAPTURE, IMPACT-II, TARGET, and CREDO) and had baseline PAD status recorded. Multivariable analyses were performed with stepwise logistic regression for 7- and 30-day outcomes and Cox regression for 6-month and 1-year events. RESULTS: In our pooled analysis of 19,867 patients undergoing PCI, 1,602 (8.1%) were previously diagnosed with PAD. Patients with PAD had higher incidences of 7-day death (1.0% vs. 0.4%; p < 0.001) or myocardial infarction (MI) (6.8% vs. 5.6%; p = 0.047), 30-day death (1.7% vs. 0.7%; p < 0.001) or MI (7.4% vs. 6.1%; p = 0.05), 6-month death (4.2% vs. 1.5%; p < 0.001) or MI (9.1%, vs. 7.7%; p = 0.048), and 1-year death (5.0% vs. 2.1%; p < 0.001). There was a trend toward higher major bleeding risk with PAD (4.8% vs. 3.9%; p = 0.06). With multivariable analyses, PAD remains a significant predictor of mortality at 30 days (hazard ratio [HR] 1.67, 95% confidence interval [CI] 1.03 to 2.70; p = 0.039), 6 months (HR 1.76, 95% CI 1.31 to 2.37; p < 0.001), and 1 year (HR 1.46, 95% CI 1.08 to 1.96; p = 0.013). CONCLUSIONS: The presence of PAD is associated with higher rates of post-PCI death and MI, and is an independent predictor of short- and long-term mortality.     

Multifocal osseous tuberculosis involving hand and feet

A rare case of multifocal cystic tuberculosis of hands and feet is presented in an adolescent female. The presence of multiple lytic areas mimicked secondary metastases and biopsy remained the mainstay for final diagnosis.     

Perioperative complications with the bone-anchored hearing aid.

OBJECTIVE: To discuss perioperative complications associated with the bone-anchored hearing aid (BAHA) and their management. STUDY DESIGN AND SETTING: A retrospective review of 58 patients who underwent implantation of BAHA for unilateral conductive, mixed, or sensorineural hearing losses was performed at a tertiary referral center. RESULTS: Between September 2003 and June 2005, 58 patients underwent implantation of a BAHA. There were 30 female and 28 male patients, with a mean age of 48 years (range 8-80 years). Complications occurred in 19% (11/58) of patients. Most adverse events were seen early in the series. The most common complication, partial or complete loss of the skin graft, occurred in 10% (6/58) of patients. These were managed successfully with local wound care. Five percent (3/58) of patients had skin growth over the abutment. Two of these cases were managed with office debridement, whereas 1 patient required revision under general anesthesia. There was implant extrusion in 3% (2/58) of patients, and both of these patients later underwent successful reimplantation. All patients had their implant activated 3 months after surgery. There were no perioperative or postoperative deaths. CONCLUSION: Complications related to BAHA implantation are relatively minor and usually involve partial or complete loss of the skin graft. Most complications were successfully managed in the office.