Development of a Continuous Segmented Flow Tubular Reactor and the “Scale‐out” Concept – In Search of Perfect Powders

The synthesis of powders with controlled shape and narrow particle size distributions is still a major challenge for many industries. A continuous Segmented Flow Tubular Reactor (SFTR) has been developed to overcome homogeneity and scale‐up problems encountered when using batch reactors. Supersaturation is created by mixing the co‐reactants in a micromixer inducing precipitation; the suspension is then segmented into identical micro‐volumes by a non‐miscible fluid and sent through a tube. These micro‐volumes are more homogeneous when compared to large batch reactors leading to narrower size distributions, better particle morphology, polymorph selectivity and stoichiometry. All these features have been demonstrated on single tube SFTR for different chemical systems. To increase productivity for commercial application the SFTR is being “scaled‐out” by multiplying the number of tubes running in parallel instead of scaling‐up by increasing their size. The versatility of the multi‐tube unit will allow changes in type of precipitate with a minimum of new investment as new chemistry can be researched, developed and optimised in a single tube SFTR and then transferred to the multi‐tube unit for powder production.     

Capillarovenous angioma of the maxillary sinus. Apropos of a case with review of the literature

Metabolic side-effects of antihypertensive drugs may increase the risk of coronary heart disease despite an adequate blood pressure reduction. Since combinations of different antihypertensive drugs are often necessary and frequently used, we performed a randomized study comparing the effects of a fixed combination of hydrochlorothiazide and sotalol (group A), or hydrochlorothiazide and captopril (group B) on blood pressure and on lipid and glucose metabolism in 40 men with essential hypertension over 1 year. Significant blood pressure reductions (p < 0.001) were achieved in both treatment groups: from 160/105 to 128/88 mmHg in group A (mean doses: hydrochlorothiazide 33 and sotalol 197 mg) and from 162/106 to 135/89 mmHg in group B (hydrochlorothiazide 33 and captopril 64 mg) after 12 months, respectively. No significant changes in body weight were observed in either treatment group. Triglycerides increased (p < 0.05) in both treatment groups (from 183 to 262 mg/dl in A, and from 160 to 196 mg/dl in B) and HDL cholesterol decreased (p < 0.001 and < 0.05) in both groups (from 45.1 to 35.7 mg/dl in A, and from 49.3 to 46.3 mg/dl in B), whereas LDL cholesterol increased significantly (p < 0.05) only in group A from 153 to 164 mg/dl. No significant changes were observed in total cholesterol nor in lipoprotein(a) concentrations in either treatment group. Fasting plasma glucose and hemoglobin A1 increased significantly (p < 0.05) only in group A after 1 year of treatment (from 91.6 to 98.0 mg/dl, and from 6.3 to 6.9%, respectively). Serum levels of creatinine and potassium decreased, and uric acid increased significantly under either combination. Our data show that the diuretic/beta-blocker combination has adverse effects on lipid and glucose metabolism after long-term therapy. The effects of the diuretic/ACE inhibitor combination on lipid metabolism are less pronounced and there are no adverse effects on glucose metabolism. However, the ACE inhibitor component could not completely counteract the metabolic effects of the diuretic. Both combinations have no effects on Lp(a). We conclude that the combination of hydrochlorothiazide with an ACE inhibitor has a better metabolic profile for the treatment of essential hypertension than the combination with a beta-blocker.     

Metabolic Syndrome: Updates on Pathophysiology and Management in 2021

Metabolic syndrome (MetS) forms a cluster of metabolic dysregulations including insulin resistance, atherogenic dyslipidemia, central obesity, and hypertension. The pathogenesis of MetS encompasses multiple genetic and acquired entities that fall under the umbrella of insulin resistance and chronic low-grade inflammation. If left untreated, MetS is significantly associated with an increased risk of developing diabetes and cardiovascular diseases (CVDs). Given that CVDs constitute by far the leading cause of morbidity and mortality worldwide, it has become essential to investigate the role played by MetS in this context to reduce the heavy burden of the disease. As such, and while MetS relatively constitutes a novel clinical entity, the extent of research about the disease has been exponentially growing in the past few decades. However, many aspects of this clinical entity are still not completely understood, and many questions remain unanswered to date. In this review, we provide a historical background and highlight the epidemiology of MetS. We also discuss the current and latest knowledge about the histopathology and pathophysiology of the disease. Finally, we summarize the most recent updates about the management and the prevention of this clinical syndrome.     

Synthesis of fractional Laguerre basis for system approximation

Fractional differentiation systems are characterized by the presence of non-exponential aperiodic multimodes. Although rational orthogonal bases can be used to model any L₂[0,∞[ system, they fail to quickly capture the aperiodic multimode behavior with a limited number of terms. Hence, fractional orthogonal bases are expected to better approximate fractional models with fewer parameters. Intuitive reasoning could lead to simply extending the differentiation order of existing bases from integer to any positive real number. However, classical Laguerre, and by extension Kautz and generalized orthogonal basis functions, are divergent as soon as their differentiation order is non-integer. In this paper, the first fractional orthogonal basis is synthesized, extrapolating the definition of Laguerre functions to any fractional order derivative. Completeness of the new basis is demonstrated. Hence, a new class of fixed denominator models is provided for fractional system approximation and identification.     

Waterpipe smoking: construction and validation of the Lebanon Waterpipe Dependence Scale (LWDS-11).

Waterpipe smoking is becoming fashionable in Lebanon, but no studies have studied nicotine dependence related to waterpipe smoking. A score was constructed from 21 items and subsequently submitted to two factor analyses, which led to the extraction of four factors. Reliability and test-retest reproducibility were measured. Convergent construct validity and discriminant validity also were assessed for different smokers' samples. The Lebanon Waterpipe Dependence Scale-11 (LWDS-11) was composed of four subscales, the first representing nicotine dependence, the second negative reinforcement, the third psychological craving, and the fourth positive reinforcement. Internal consistency and test-retest reproducibility were adequate, and the subscales correlated adequately with measurements of nicotine metabolites, exhaled carbon monoxide levels, and the frequency of waterpipe smoking. The LWDS-11 discriminated between mild, moderate, and heavy waterpipe smokers, based on a threshold score of 10. Results were biologically and psychologically sound. This is the first scale to characterize waterpipe dependence. With further improvement and confirmation, it could become a useful clinical and epidemiological tool.     

Asphalt Works Subcontracting Disputes in Large Construction Programs

Subcontracting is a common, and sometimes warranted, practice on large construction projects. However, it is also well recognized that disputes are likely to develop between subcontractors and general contractors in trying to achieve target objectives of cost, quality, and time. This paper tackles quality- and time-related disputes that are peculiar to the case of subcontracting asphalt works under a large construction program, such as that of a new airport construction. In particular, it reports on disagreements regarding the achieved thickness and surface smoothness of the constructed asphalt concrete layer, and on activity-interfacing and delay-attribution issues resulting from improper contractual and scheduling practices. Factors believed to be relevant to both classes of disputes are identified, and analyses are offered to pinpoint significant anomalies. Finally, arguments are developed and recommendations given, that reflect best industry practices whose application could help minimize the likelihood of facing such disputes in the future.     

Vacuum Technology Considerations For Mass Metrology

Vacuum weighing of mass artifacts eliminates the necessity of air buoyancy correction and its contribution to the measurement uncertainty. Vacuum weighing is also an important process in the experiments currently underway for the redefinition of the SI mass unit, the kilogram. Creating the optimum vacuum environment for mass metrology requires careful design and selection of construction materials, plumbing components, pumping, and pressure gauging technologies. We review the vacuum technology¹ required for mass metrology and suggest procedures and hardware for successful and reproducible operation.     

Gateway Placement Optimization in Wireless Mesh Networks With QoS Constraints

In a wireless mesh network (WMN), the traffic is aggregated and forwarded towards the gateways. Strategically placing and connecting the gateways to the wired backbone is critical to the management and efficient operation of a WMN. In this paper, we address the problem of gateways placement, consisting in placing a minimum number of gateways such that quality-of-service (QoS) requirements are satisfied. We propose a polynomial time near-optimal algorithm which recursively computes minimum weighted Dominating Sets (DS), while consistently preserving QoS requirements across iterations. We evaluate the performance of our algorithm using both analysis and simulation, and show that it outperforms other alternative schemes by comparing the number of gateways placed in different scenarios     

Interval observer framework for fault-tolerant control of linear parameter-varying systems

This paper addresses the problem of passive fault-tolerant control for linear parameter-varying systems subject to actuator faults. The FTC, based on a linear state feedback, is designed to compensate the impact of actuator faults on system performance by stabilising the closed-loop system using interval observers. The design of interval observers is based on the discrete-time Luenberger observer structure, where uncertainties and faults with known bounds are considered. Sufficient conditions for the existence of the proposed observer are explicitly provided. Simulation results are presented to show the effectiveness of the proposed approach.