Synthesis of nucleoside analogues in a ball mill: fast, chemoselective and high yielding acylation without undesirable solvents

The chemoselective acylation of primary aliphatic amines has been achieved in under ten minutes (and for aromatic amines under 120 min) using vibration ball-milling, avoiding undesirable solvents which are typically employed for such reactions (e.g. DMF). Under optimised conditions, the synthesis of amides in the presence of both primary and secondary alcohol functions was achieved in high to excellent yields (65-94%). Overall, the methods described have significant practical advantages over conventional approaches based upon bulk solvents including greater yields, higher chemoselectivity and easier product separation.

Rapid synthesis of nucleotide pyrophosphate linkages in a ball mill

Using a ball mill, rapid, atom-economic coupling between adenosine-5'-phosphoromorpholidate and phosphorylated ribose derivatives as their sodium or barium salts was achieved. Facile purification by reversed-phase HPLC enabled product isolation within hours.

Weighing China’s export basket: The domestic content and technology intensity of Chinese exports

In this paper we use new, detailed, and comprehensive linked firm-transaction data to measure the domestic content and technology intensity of Chinese exports over the period 2000–2007. We evaluate the extent of value-added in China’s exports, using a modification of a method proposed by Hummels et al. (2001) which takes into account the prevalence of processing firms. In addition, we provide new estimates of the skill-and technology-intensity of China’s exports. Our estimates of value-added suggest that the domestic content of China’s exports increased from only 53% to about 60% over the period 2003–2006. Our cross-firm analysis reveals that processing exporters have value-added shares approximately 50% lower than non-processing exporters, even after accounting for ownership, location, and industry. We also show that Chinese exports have become increasingly sophisticated, largely driven by skill and technology improvement within industries.

Pattern stability and error correction during in-phase and antiphase four-ball juggling

The authors studied pattern stability and error correction during in-phase and antiphase 4-ball fountain juggling. To obtain ball trajectories, they made and digitized high-speed film recordings of 4 highly skilled participants juggling at 3 different heights (and thus different frequencies). From those ball trajectories, the authors determined and analyzed critical events (i.e., toss, zenith, catch, and toss onset) in terms of variability of point estimates of relative phase and temporal correlations. Contrary to common findings on basic instances of rhythmic interlimb coordination, in-phase and antiphase patterns were equally variable (i.e., stable). Consistent with previous findings, however, pattern stability decreased with increasing frequency. In contrast to previous results for 3-ball cascade juggling, negative lag-one correlations for catch-catch intervals were absent, but the authors obtained evidence for error corrections between catches and toss onsets. That finding may have reflected participants' high skill level, which yielded smaller errors that allowed for corrections later in the hand cycle.

Market Basket Survey Shows Elevated Levels of As in South Central U.S. Processed Rice Compared to California: Consequences for Human Dietary Exposure:consequences for human dietary exposure

We report the largest market basket survey of arsenic (As) in U.S. rice to date. Our findings show differences in transitional-metal levels between polished and unpolished rice and geographical variation in As and selenium (Se) between rice processed in California and the South Central U.S. The mean and median As grain levels for the South Central U.S. were 0.30 and 0.27 µg As g-1, respectively, for 107 samples. Levels for California were 41% lower than the South Central U.S., with a mean of 0.17 µg As g-1 and a median of 0.16 µg As g-1 for 27 samples. The mean and median Se grain levels for the South Central U.S. were 0.19 µg Se g-1. Californian rice levels were lower, averaging only 0.08 and 0.06 µg Se g-1 for mean and median values, respectively. The difference between the two regions was found to be significant for As and Se (General Linear Model (GLM):? As p < 0.001; Se p < 0.001). No statistically significant differences were observed in As or Se levels between polished and unpolished rice (GLM:? As p = 0.213; Se p = 0.113). No significant differences in grain levels of manganese (Mn), cobalt (Co), copper (Cu), or zinc (Zn) were observed between California and the South Central U.S. Modeling arsenic intake for the U.S. population based on this survey shows that for certain groups (namely Hispanics, Asians, sufferers of Celiac disease, and infants) dietary exposure to inorganic As from elevated levels in rice potentially exceeds the maximum intake of As from drinking water (based on consumption of 1 L of 0.01 mg L-1 In. As) and Californian state exposure limits. Further studies on the transformation of As in soil, grain As bioavailability in the human gastrointestinal tract, and grain elemental speciation trends are critical.

Scaled Heavy-Ball Acceleration of the Richardson-Lucy Algorithm

The Richardson-Lucy algorithm is one of the most important algorithms in the image deconvolution area. However, one of its drawbacks is slow convergence. A very significant acceleration is obtained by the technique proposed by Biggs and Andrews (BA), which is implemented in the deconvlucy function of the Image Processing MATLAB toolbox. The BA method was developed heuristically with no proof of convergence. In this paper, we introduce the Heavy-Ball (H-B) method for Poisson data optimization and extend it to a scaled H-B method, which includes the BA method as a special case. The method has proof of the convergence rate of O(k-2), where k is the number of iterations. We demonstrate the superior convergence performance of the scaled H-B method on both synthetic and real 3D images.

Better understanding of mechanochemical reactions: Raman monitoring reveals surprisingly simple 'pseudo-fluid' model for a ball milling reaction

Quantitative monitoring of a mechanochemical reaction by Raman spectroscopy leads to a surprisingly straightforward second-order kinetic model in which the rate is determined simply by the frequency of reactive collisions between reactant particles.

Balls to the wall: How acoustic information from a ball in motion guides interceptive movement in people with Parkinson’s disease

Previous research has shown that Parkinson's disease (PD) patients can increase the speed of their movement when catching a moving ball compared to when reaching for a static ball (Majsak et al., 1998). A recent model proposed by Redgrave et al. (2010) explains this phenomenon with regard to the dichotomic organization of motor loops in the basal ganglia circuitry and the role of sensory micro-circuitries in the control of goal-directed actions. According to this model, external visual information that is relevant to the required movement can induce a switch from a habitual control of movement toward an externally-paced, goal-directed form of guidance, resulting in augmented motor performance (Bienkiewicz et al., 2013). In the current study, we investigated whether continuous acoustic information generated by an object in motion can enhance motor performance in an arm reaching task in a similar way to that observed in the studies of Majsak et al. (1998, 2008). In addition, we explored whether the kinematic aspects of the movement are regulated in accordance with time to arrival information generated by the ball's motion as it reaches the catching zone. A group of 7 idiopathic PD (6 male, 1 female) patients performed a ball-catching task where the acceleration (and hence ball velocity) was manipulated by adjusting the angle of the ramp. The type of sensory information (visual and/or auditory) specifying the ball's arrival at the catching zone was also manipulated. Our results showed that patients with PD demonstrate improved motor performance when reaching for a ball in motion, compared to when stationary. We observed how PD patients can adjust their movement kinematics in accordance with the speed of a moving target, even if vision of the target is occluded and patients have to rely solely on auditory information. We demonstrate that the availability of dynamic temporal information is crucial for eliciting motor improvements in PD. Furthermore, these effects appear independent from the sensory modality through-which the information is conveyed. 

Facilitation of nucleoside and nucleotide chemistry by ball milling

Nucleoside Azide-Alkyne Cycloaddition Reactions Under Solvothermal Conditions or Using Copper Vials in a Ball Mill

Novel nucleoside analogues containing photoswitchable moieties were prepared using 'click' cycloaddition reactions between 5 '-azido-5 '-deoxythymidine and mono- or bis-N-propargylamide-substituted azobenzenes. In solution, high to quantitative yields were achieved using 5mol% Cu(I) in the presence of a stabilizing ligand. 'Click' reactions using the monopropargylamides were also effected in the absence of added cuprous salts by the application of liquid assisted grinding (LAG) in metallic copper reaction vials. Specifically, high speed vibration ball milling (HSVBM) using a 3/32('') (2.38mm) diameter copper ball (62mg) at 60Hz overnight in the presence of ethyl acetate lead to complete consumption of the 5 '-azido nucleoside with clean conversion to the corresponding 1,3-triazole.