Technical crystallization for application in pharmaceutical material engineering: Review article

In recent years, engineering the total morphology of pharmaceutical materials particles to desirable shape, size and surface area has long been actively increased because it has many advantages especially for improving physicochemical properties of Active Pharmaceutical Ingredients (APIs). This article therefore considers the potential utility of crystal engineering as a tool for controlling and designing properties of pharmaceutical solid particles in purpose to developing efficacious performance of solid dosage form, fundamentals of crystallization process, applications. In addition, understanding the relationship between molecular recognition, thermodynamic, and kinetics which controls the crystallization process so that it benefits in designing successful experiments to have desirable crystal habit for materials.     

Electrodeposition of gold from cyanide solutions on different n-GaAs crystal faces

The initial stages of the electrodeposition of gold from $\mathrm{Au}(\mathrm{CN}{)}_2^{?}$-solutions on n-GaAs were investigated by means of chronoamperometry and ex situ atomic force microscopy (AFM). Three different crystal orientations were examined, i.e. (1 1 1), $(\overline{1}\overline{1}\overline{1})$ and (1 0 0) n-GaAs. Analysis of the experimental current transients showed that the nucleation mechanism of Au on n-GaAs depends strongly on the surface orientation and the deposition potential, which was confirmed by AFM measurements. This can be explained by differences in chemical composition of the surface. Further, it was observed that the Au nuclei grow laterally, which results in a flat morphology.     

10％的盐水冰袋用于体外循环术后高热患者降温效果的研究

目的探讨采用10％的盐水冰袋冰敷在体外循环术后高热患者物理降温中的效果。方法对124例体外循环术后高热患者的物理降温效果进行比较，研究组60例，应用10％的盐水冰袋作为物理降温的用具；对照组64例，使用传统的橡胶冰袋冰敷作为物理降温用具。记录降温后不同时间患者体温下降的情况。结果2组病例冰枕冰敷后0．5，1．5h降温效果差异无显著性（P〉0．05）；冰枕冰敷后2．5，4．0h降温效果差异有显著性（P〈0．05）。结论10％的盐水冰袋冰敷具有降温效果好、持续时间长，冰袋内为霜水，患者感觉舒适，值得临床推广应用。     

Small-Town Doctor Provides Big-Time Care

In brief: Two related studies were conducted to determine whether fast walking is intense enough to elicit a training heart rate (THR), which is defined as ≥ 70% of maximal heart rate. In one study, 343 subjects (165 men, 178 women) walked a mile as fast as possible. Ninety-one percent of all the women and 83% of men aged 50 and older reached a THR. In the second study, ten men with high V o₂ max values were instructed to achieve and maintain a THR and were provided with visual feedback of their heart rate (HR) during a 30-minute walk. These subjects maintained a THR for an average of 25 minutes during the walk. Thus, it seems that fast walking may indeed offer an adequate aerobic training stimulus for most adults.     

The effect of ice stimulation on sensory loss in chronic stroke patients—a feasibility study

Objectives

Ice stimulation has often been used in sensory bombardment programmes after stroke. This feasibility study explored the effects of ice as a single stimulus on disturbed wrist position sense, sensation of light touch and temperature discrimination of the affected hand.

Design

A multiple baseline single case study design across subjects.

Setting

Physiotherapy department at the Royal Star and Garter Home.

Participants

Four patients following cerebrovascular accident with left hemiparesis.

Methods

Eight baseline measurements were collected over a minimum of 8 days. The intervention phase was started for the first, second, third and fourth subjects staggered on the 8th, 11th, 13th and 15th days of the study, respectively.

Intervention

The intervention phase involved daily short, repeated ice-water immersions of each subject's affected hand.

Main outcome measure

Repeated measurements of wrist position sense, sensation of light touch and temperature discrimination.

Results

Visual and statistical analysis indicated that changes of wrist position error were neither significant nor consistent across subjects. Results for sensation of light touch were inconclusive: one subject improved and two subjects showed deterioration. Temperature discrimination of warm stimuli improved in one subject.

Conclusion

These observations suggest that ice-water immersions of the affected hand did not improve wrist position sense in three chronic stroke patients. Further exploration of the effects of ice stimulation on disturbed sensation of light touch and temperature after stroke is justified.     

止血镇痛冰块的研制及临床应用效果观察

目的 寻找扁桃体摘除术后局部止血镇痛的有效方法。方法 自行研制了止血镇痛冰块(下称药冰)。100例扁桃体摘除术后患者(观察组)术后2小时起含化药冰,每1～2小时1次,每日8～12次;对照组(50例同期行扁桃体摘除术的患者)术后2小时舌根部含化冰淇淋或雪糕。观察两组术后出血疼痛、伤口愈合等情况。结果 观察组术后疼痛明显减轻,24小时出血量少,进食情况较好,与对照组相关指标比较,P均<0.01。结论药冰制作简单、价格低廉、无异味,止血、镇痛、促伤口愈合效果可靠,优于传统方法。     

Critical slowing down suggests that the western Greenland Ice Sheet is close to a tipping point

The Greenland Ice Sheet (GrIS) is a potentially unstable component of the Earth system and may exhibit a critical transition under ongoing global warming. Mass reductions of the GrIS have substantial impacts on global sea level and the speed of the Atlantic Meridional Overturning Circulation, due to the additional freshwater caused by increased meltwater runoff into the northern Atlantic. The stability of the GrIS depends crucially on the positive melt-elevation feedback (MEF), by which melt rates increase as the overall ice sheet height decreases under rising temperatures. Melting rates across Greenland have accelerated nonlinearly in recent decades, and models predict a critical temperature threshold beyond which the current ice sheet state is not maintainable. Here, we investigate long-term melt rate and ice sheet height reconstructions from the central-western GrIS in combination with model simulations to quantify the stability of this part of the GrIS. We reveal significant early-warning signals (EWS) indicating that the central-western GrIS is close to a critical transition. By relating the statistical EWS to underlying physical processes, our results suggest that the MEF plays a dominant role in the observed, ongoing destabilization of the central-western GrIS. Our results suggest substantial further GrIS mass loss in the near future and call for urgent, observation-constrained stability assessments of other parts of the GrIS.

During the last century, the Greenland Ice Sheet (GrIS) has lost mass at an accelerating rate (1, 2). The mass loss is caused by solid ice discharge into the North Atlantic and surface melting due to increasing temperatures. The relative contribution of the latter has increased from 42% before 2005 to 68% between 2009 and 2012, and surface runoff caused 84% of the increase in mass reduction since 2009 (3). The complete melting of the GrIS would cause a global sea level rise of more than 7 m (4, 5). Continued melting of the GrIS has been suggested to potentially lead to a collapse of the Atlantic Meridional Overturning Circulation via increased freshwater flux into the North Atlantic (6, 7), which may, in turn, trigger a cascade of transitions in additional tipping elements such as the Amazon rainforest and the tropical monsoon systems (6, 8–10).In addition to the centennial-scale variability associated with the increasing trend in mean temperatures related to anthropogenic climate change, the pace of mass loss has decadal-scale fluctuations caused by natural variations in external oceanic and atmospheric forcing. The imprints of these natural, decadal-scale fluctuations are spatially heterogeneous across the GrIS. Since the early 2000s, periods of persistently negative phases of the North Atlantic Oscillation (NAO) and a positive phase of the East Atlantic Pattern (11) have led to a weakening and southward shift of the jet stream, and more persistent blocking (12) over Greenland during summer, resulting in overall increased mass reduction rates (2, 13). On the other hand, a slowing down of mass loss since 2013—which inverted again in 2019—was caused by more periods with a persistent positive NAO (14). Moreover, recent observations show that the Jakobshavn glacier has been advancing again since 2016 due to anomalous wintertime heat loss in the boundary current around southern Greenland (15). However, these natural fluctuations do not have a sustained impact on melt rates comparable to the longer-term trend toward overall increasing melt rates caused by anthropogenic global warming (Fig. 1A).Open in a separate windowFig. 1.(A) Summer sea level temperatures from the Ilulissat station in CWG (25) (blue curves) and Arctic temperature anomalies (26) (red curves). The linear trend of the station data (dashed blue curve) corresponds to 1.3 °C warming per century. Arctic temperature anomalies are shown only for comparison; only the station data (blue curves) are used for our analysis. (B) Melt rates from the CWG ice core stack (blue curve) and the NU peninsula core (red curve), given as z scores with respect to a normal distribution (18). (C) Detrended logarithmic CWG (blue curve) and NU (red curve) melt rates. A Gaussian filter with bandwidth σ=30 y was used for detrending. The runoff and melt time series are preprocessed in this way before computing the EWS indicators to exclude potential biases by underlying trends; in particular, we take the logarithm of the melt rates in order to account for skewed data distributions. (D) The variance of the CWG (blue curves) and NU (red curves) melt rates. (E) The AC1 of the CWG (blue curves) and NU (red curves) melt rates. Note that the AC1, despite a significantly positive trend, appears to have at least temporarily stabilized in the last few decades. It should be noted, however, that the AC1 is generally influenced by (multi)decadal variability (27). The window size for computing the variance and the AC1 is w=70 y, and values are plotted at the windows’ endpoints. Data for the first w=70 y are omitted to ensure that all windows contain the same number of data points. The dashed lines in D and E indicate linear trends of the variance and AC1, and P values for positive slopes as determined from a phase surrogate test are indicated in the legend (see Materials and Methods). The statistical significance of the positive trends is robust across wide ranges of the bandwidth σ and the sliding window size (SI Appendix, Fig. S1).Early model simulations suggest that melting of the GrIS is inevitable beyond a critical global mean temperature threshold of 0.8 °C to 3.2 °C above preindustrial levels, with a best estimate of 1.6 °C (16). More recent comprehensive modeling results show that, for the representative concentration pathway 8.5 (RCP8.5), the GrIS melts entirely until AD 3000 (5). Arctic temperatures have increased more than the global average (17) (Fig. 1A), and the nonlinear increase in GrIS melt rates and runoff that have recently been detected (18) (Fig. 1B) suggests that the critical temperature threshold may be closer than previously thought. We emphasize that the surface mass balance turning negative is not a necessary condition for stability loss, and the temperature may reach a critical threshold years before a turning point in the mass balance (16).Idealized models of critical transitions in natural systems suggest that the loss of stability of an equilibrium (fixed point) is observable before the abrupt transition (19). In dynamical systems with random forcing, one can show that, if a system approaches a bifurcation where an equilibrium point loses its stability, the variance of the fluctuations around the equilibrium will increase, as will the characteristic decay time of the autocorrelation function of these fluctuations. The change in dynamics that occurs as stability is lost is often called critical slowing down, and the associated statistical precursor signs in terms of rising variance and lag-one autocorrelation (AC1) are called early-warning signals (EWS) (19). Such statistical EWS associated with critical slowing down are, for example, detectable in the temperature proxy from the North Greenland Ice Core Project before several of the Dansgaard–Oeschger events of the last glacial interval (20, 21), as well as before other abrupt transitions in past climates (22). In the context of anthropogenic global warming, EWS are expected to precede potential abrupt transitions in the Earth system’s major tipping elements, such as the polar ice sheets, the Atlantic Meridional Overturning Circulation, or the tropical monsoon systems (23). We investigate here a possible tipping point for the GrIS based on the theory of critical slowing down.In the following, we will first show that central-western Greenland (CWG) melt rates exhibit robust and significant EWS. We then reconstruct the corresponding CWG ice sheet height changes and show that they can be captured well by a simple model focusing on the melt elevation feedback (MEF). We then demonstrate that pronounced EWS can also be found in the fluctuations of the reconstructed ice sheet height around the equilibrium of the model and show that these EWS are consistent with the theoretical expectations provided by the MEF model.     

Cultural adaptation, compounding vulnerabilities and conjunctures in Norse Greenland

Norse Greenland has been seen as a classic case of maladaptation by an inflexible temperate zone society extending into the arctic and collapse driven by climate change. This paper, however, recognizes the successful arctic adaptation achieved in Norse Greenland and argues that, although climate change had impacts, the end of Norse settlement can only be truly understood as a complex socioenvironmental system that includes local and interregional interactions operating at different geographic and temporal scales and recognizes the cultural limits to adaptation of traditional ecological knowledge. This paper is not focused on a single discovery and its implications, an approach that can encourage monocausal and environmentally deterministic emphasis to explanation, but it is the product of sustained international interdisciplinary investigations in Greenland and the rest of the North Atlantic. It is based on data acquisitions, reinterpretation of established knowledge, and a somewhat different philosophical approach to the question of collapse. We argue that the Norse Greenlanders created a flexible and successful subsistence system that responded effectively to major environmental challenges but probably fell victim to a combination of conjunctures of large-scale historic processes and vulnerabilities created by their successful prior response to climate change. Their failure was an inability to anticipate an unknowable future, an inability to broaden their traditional ecological knowledge base, and a case of being too specialized, too small, and too isolated to be able to capitalize on and compete in the new protoworld system extending into the North Atlantic in the early 15th century.